Volume 8, Issue 1 , Pages 27-35, February 2003
Redo mitral valve repair or replacement through the right chest☆☆☆
Article Outline
The right thoracotomy approach for mitral valve surgery was an incision used in the 1950s and 1960s in some of the initial series of mitral valve operations.1 When the obvious advantages of the median sternotomy for most patients became apparent, this approach was for the most part abandoned. However, there are many clinical situations in the reoperative mitral valve setting where a different approach other than a median sternotomy is not only helpful, but often times essential for patients undergoing complicated reoperation mitral valve surgery to prevent injury to underlying structures and facilitating exposure of the mitral valve.2, 3, 4 Consideration of this approach should include patients who have had: 1) a previously implanted aortic valve prosthesis or bioprosthesis, 2) patent coronary bypass grafts, especially the left internal mammary to left anterior descending bypass, 3) prior multiple reoperations through the sternum, making the right ventricle and aorta adhesive to the underside of the sternum, and 4) prior mediastinal infection, which also may cause a severe adhesive process between the cardiac structures and the underside of the sternum. These are the most common conditions in which the right anterior thoracotomy approach, utilizing peripheral cardiopulmonary bypass cannulation and cold fibrillation, may be a safer, more rapid technique for complicated mitral valve surgery.
This article will describe the technical features of this operation and present some of the latest experiences at the Brigham and Women's Hospital with this procedure.
Clinical summary
From January 1992 to July 2002, 143 patients have undergone reoperation mitral valve surgery through a right thoracotomy approach using femoro-femoral bypass and cold ventricular fibrillation. A summary of these patients appears in the Table.
Table 1. Right thoracotomy MVP/MVR 1992-2002
| NO: | 143 |
| MALE: | 87 |
| FEMALE: | 56 |
| AGE: | 24-89 56.5 |
| INDICATIONS | |
 PRIOR AVR | 31 |
| PRIOR CABG | 78 |
| PRIOR MULT REOP OR MEDIASTINITIS | 34 |
| # PREVIOUS OPERATIONS | |
| 1 | 89 |
| 2 | 32 |
| 3 | 22 |
| OPERATIONS | |
| MVR | 95 |
| MVP | 48 |
| OP DEATH (30 DAY) | 15/143 (10.5%) |
| MI | 3/143 (2%) |
| STROKE | 5/143 (3.5%) |
Mitral valve replacement and mitral valve repair operations are performed through this incision, particularly for patients who have undergone prior coronary artery bypass and return with ischemic cardiomyopathy and secondary mitral regurgitation, requiring only annululoplasty operations (78 of 143).
The overall 30-day operative mortality was 15 of 143 (10.4%), with a mortality of 7.5% (7 of 93) during the past 5 years.
Preoperative preparation
Many of these patients have severe pulmonary hypertension and a number of other sequelae of severe mitral valve disease and/or ischemic cardiomyopathy. The patients should be screened for any pulmonary disease. A prior right thoracotomy complicates the operation, but this approach has been used even in patients with a prior thoracotomy in whom the risk of a reoperative sternotomy is deemed to be much greater than that of the thoracotomy. General preparation for cardiopulmonary bypass operations is extremely important for these patients and an extra day or two in the hospital, despite current trends toward reducing length of stay, is often critical in preparing these patients for surgery. Complete left and right cardiac catheterization and echocardiography are standard before operation.
Surgical technique
1 The patient undergoes general anesthesia with a bronchial blocker to allow one lung anesthesia and right lung deflation to expose the heart. The patient is positioned for a right anterior thoracotomy in an approximately 45° position. The right and left groin is prepped for peripheral cannulation and the arm is placed above the head as shown. Monitoring lines include radial artery, urinary catheter, central venous, and a pulmonary artery catheter. Transesophageal echocardiogram (TEE) is used in every patient. The incision is made in the fourth intercostal space high enough to insure that the upper part of the left atrium is in the field. Moist laparotomy pads are used to depress and retract the lung and diaphragm. After systemic heparinization, the patient is cannulated for cardiopulmonary bypass. The preferred cannulation is the right femoral artery and femoral vein. This technique has been used successfully in more than 1,500 reoperations over the last 10 years at the Brigham. Instead of clamping and incising the vessels, purse-strings of 5-to-0 Prolene are placed in both the artery and vein and then the Gensini needle technique is used, first introducing a needle, then a wire, then the perfusion catheter. When these catheters are withdrawn, the purse strings are simply tied. Only a single right atrial catheter (24 Fr) is inserted via the femoral vein. Vacuum-assisted venous suction in the cardiopulmonary bypass circuit is utilized, so only a 24-Fr catheter is needed for venous drainage and a 20- or 22-Fr cannula in the femoral artery. If the femoral artery is diseased, or the descending aorta has loose atherosclerotic material (shown by TEE), which might embolize, retrograde femoral artery cannulation is contra-indicated. Then, either the right axillary artery or in a few cases, the right-hand aspect of the ascending aorta has been cannulated directly.
2 The right femoral vein cannula is inserted into the body of the right atrium at the entrance of the superior vena cava under TEE guidance, so that there is adequate drainage of both the inferior and superior vena cava. If this is insufficient, then a small 24-Fr right-angle cannula can be inserted into the superior vena cava directly.
3 The pericardium has been incised over the atrium and reflected back toward the right and left side and held there with sutures of 2-to-0 silk. In cases where exposure may be less than optimal due to the large size of the patient, the sternum may be partially or totally transected in part and the right mammary artery doubly ligated. Once the patient is on bypass, the patient is cooled to 25° to 28°C. At this point, the heart usually fibrillates and the left atrium is opened. If the heart does not fibrillate, an electrical fibrillator may be applied to the underside of the minimally dissected right ventricle. This technique is more difficult if there is aortic regurgitation. To deal with aortic regurgitation, we cool to 15° to 20°C and go to lower cardiopulmonary bypass flows; in a few instances (10 of 143), we have dissected the aorta out and placed an aortic cross-clamp, although some have done this routinely3. This is more difficult if there are multiple vein grafts and is obviated in most instances. After the left atrium is opened, a flexible, wire-reinforced, small-suction vent is placed in the most dependent portion of the left atrium. The valve is then inspected and evaluated for repair or replacement. A black silk retracts the lateral aspect of the left atrial wall and the flexible, wire-reinforced vent is held in place and out of the way by this suture.
4 The Cosgrove® ring is utilized and approximately nine mattress sutures are placed beginning from left and right trigone, working toward the middle. The undersized annuloplasty ring is usually sufficient to make a competent valve because this regurgitation is due to ventricular dilation. Other reparative techniques described previously5, 6, 7 can be used as well. This includes P2 resection, sliding valvuloplasty, and artificial chordae. Anterior leaflet repair is possible, but due to the somewhat more difficult exposure, repair may be more problematic to achieve a good result.
5 With a bioprosthetic valve, noneverting sutures are used and with a prosthetic bi-leaflet valve as shown, such as the St. Jude valve, everting sutures are used.
6 Following repair or replacement of the valve, deairing procedures must be meticulously performed. TEE monitors ventricular distention, repair or replacement competency post-bypass, and most importantly, intracardiac air removal. A suction vent is placed in the ascending aorta (if available), but most importantly, we place a small red rubber catheter through the prosthetic valve, the bioprosthetic valve or the repaired valve, and advance it to the apex of the left ventricle. Following positioning of the patient with the head slightly down and in the left dependent situation, the left ventricle becomes the most dependent part of the cardiac structure and air will therefore rise to the top. CO2 is also flooded into the field during the operation and the closure,8 which aids in displacement of air to the surface.
7 Deairing maneuvers consist of alternating filling and hyperventilating the patients so as to express air out of the pulmonary veins. The monitoring of the intracardiac air by TEE is essential for this approach and it has resulted in a uniformly good record, avoiding postoperative air emboli. The total stroke rate is only 5 of 143 (3.5%) sustaining a postoperative neurologic event. Once the air has been evacuated, as determined by the TEE, the left ventricular catheter is then removed and the left atrial suture line closure is completed. Temporary pacing wires may be necessary if there is bradycardia or other conditions that seem more amenable to ventricular pacing. Temporary pacing wires may be placed on the inferior aspect of the right ventricle, which can be exposed by gentle dissection. If the patient has been in chronic atrial fibrillation, then a left-sided radio frequency ablation of atrial fibrillation can be performed at the same time as the mitral valve operation. Once the patient is off bypass, the heparin is neutralized with Protamine and the bleeding is policed in the mediastinum and the right thorax. The cannulae are removed from the groin, again using the purse-string technique rather than the transection technique. The incidence of femoral venous and femoral arterial cannulation site complications have been less than 1%.
8 The chest is closed after placement of standard chest tubes, one at the base and one at the apex of the right thorax. Regional blocks of the intercostal nerves above and below the incision site are done to help minimize postoperative pain.
Comments
This operation has proven to be a mainstay in our clinic for the treatment of the increasingly difficult population of complicated patients requiring reoperative mitral valve surgery. There continues to be debate about the advisability of doing moderate to moderately severe mitral regurgitation at the same time as coronary artery bypass grafting.9 Thus, a number of patients not treated at the time of CABG with mitral valve repair often return 2 to 5 years later with severe mitral regurgitation, requiring this operation in the presence of several patent bypass grafts. In addition, patients undergoing bioprosthetic valve replacement will be an ever increasing number of reoperations, often with previous coronary artery bypass grafts.10 Finally, patients with previously treated aortic valve disease often develop late mitral valve disease in rheumatic Marfan's disease and after endocarditis, requiring mitral valve surgery after an aortic valve procedure.
This technique is somewhat more laborious and time consuming because of the peripheral cannulation and other aspects of the incision, but it has paid off in terms of patient safety in this high-risk group of patients with preoperative pulmonary hypertension and often times low left ventricular ejection fractions. Bleeding is markedly reduced from this approach because the previous adhesive tissues are for the most part not encountered, and decreased transfusion requirements are a secondary effect.8, 9, 10, 11 Postoperatively, pulmonary dysfunction, which has often been a problem in patients with pulmonary hypertension, has not been a major long-term morbidity with this group.4
No cardioplegia is used in these patients with very occasional exceptions. We have previously published that the safety of this approach, especially with functioning left internal mammary artery/LAD grafts utilizing cold fibrillatory arrest and success, is high despite perfusing the left internal mammary artery/LAD graft during the case.11, 12
The importance of trans-esophageal echocardiogram cannot be overemphasized; it aids in cannulation guidance and is especially important to insure complete intracardiac air removal; as usual, it serves as the “gold standard” of post-bypass mitral valve competence.
The only relative contraindications for the right thoracotomy approach include patients who have moderate to severe aortic insufficiency and patients with extremely severe chronic obstructive pulmonary disease.
References
- . Mitral commissurotomy through the right thoracic approach. J Thorac Surg. 1954;27:16
- Right thoracotomy, femorofemoral bypass and deep hypothermia for re-replacement of the mitral valve. Ann Thorac Surg. 1989;48:69–71
- . Revival of right thoracotomy to approach atrio-ventricular valves in reoperations. Thorac Cardiovasc Surg. 1984;32:331
- Right thoracotomy for mitral reoperation: analysis of technique and outcome. Ann Thorac Surg. 2000;70:1970–1973
- Very long term results (more than 20 years) of valve repair with Carpentiers techniques in non-rheumatic mitral valve insufficiency. Circulation. 2001;104:I8–I11
- . Minimally invasive valve operations. Ann Thorac Surg. 1998;65:1535–1538
- Long-term results of mitral valve reconstruction for regurgitation of the myxomatous mitral valve. J Thorac Cardiovasc Surg. 1994;107:143–151
- Reoperative mitral valve surgery via right thoracotomy: decreased blood loss and improved hemodynamics (see comments). J Heart Valve Dis. 1996;5:169–173
- The impact of residual mitral regurgitation on survival after CABG and annuloplasty for ischemic mitral regurgitation. In: Presented at the American Association for Thoracic Surgery Annual Meeting Washington, DC. 2002;
- Decrease in operative risk of reoperative valve surgery. Ann Thorac Surg. 1993;56:15–20
- The preferred approach for mitral valve surgery after CABG: right thoracotomy, hyperthermia and avoidance of LIMA-LAD graft. J Heart Valve Dis. 2001;10:584–590
- Mitral valve surgery after previous CABG with functioning IMA grafts. Ann Thorac Surg. 1999;68:2243–2247
☆ Address reprint requests to Lawrence H. Cohn, MD, Division of Cardiac Surgery, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115.
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© 2003 Published by Elsevier Inc.
Volume 8, Issue 1 , Pages 27-35, February 2003
